I agree with Mateored: Avoid metal drivers, especially metal tweeters. Look for soft-domes (plastic, cloth, etc.), ribbon tweeters or the revived folded ribbon (a.k.a. Heil air motion) tweeters. Also, the sound that bothers you, which also bothers me, can result from poor crossover design or implementation, so just having non-metal drivers is no guaranty of a winner. Some brands to audition:
Reference 3a
GoldenEar (although they really don't have a "monitor" yet)
Silverline Audio (good luck finding a dealer)
Dynaudio
Mark & Daniel
Quad
Kirksaeter
Morel
Sonus Faber
LSA
Nola (Boxers)
Vienna Acoustics
Fritz
Spendor
Opera
Anthony Gallo Acoustics
Reference 3a
GoldenEar (although they really don't have a "monitor" yet)
Silverline Audio (good luck finding a dealer)
Dynaudio
Mark & Daniel
Quad
Kirksaeter
Morel
Sonus Faber
LSA
Nola (Boxers)
Vienna Acoustics
Fritz
Spendor
Opera
Anthony Gallo Acoustics